When it was first explained I was looking for something completely different as I was not aware of any quota limitations but I now see where the issue lies. All Membership types have different settings.
Awhile back a Regular Standard Membership could never use Attachments but could upload using a Third Party Host Website for uploading their images and placing the links in the Forums so the content would show on a post. As time went along Admin had added the Standard Membership to upload Attachments directly by using the Attachment feature that's in the area where posts are made.
The Standard Membership has an Attachment Quota of 97.66MB. As Standard Members upload their images the size of the upload gets deducted from their Attachment Quota. {Example: 97.66MB Allowable, upload a 2MB image the Attachment Quota drops by 2MB to 95.66MB. The more that gets uploaded will bring the Attachment Quota for that Membership down to almost 0.}
Other Membership types such as Hero Memberships and Paid Memberships do not have Attachment Quotas so they have Unlimited Uploading but there is Upload Limits on the Size of the File that can be Uploaded at any one time.
Since Hero Memberships are no longer offered the only other type of Membership available is a Paid Membership.
Hopefully this explains the process of how Memberships at xCamFan.com work.